Walk behind trencher for limited depth installations

ABSTRACT

This invention relates to mechanized drive units and a trenching attachment thereto for installing low-voltage wire, cable or fiber optic media. It is specifically an improved mechanized drive unit and attachment that can vary its driving speed and trenching speed independently, and have an extremely narrow width of cut so as to vastly improve the cutting operation. Additionally, it improves the operation in existing residential or light commercial installations by being small and having an improved turning radius as to better negotiate and maneuver. Lastly, it improves the consistency of wire and cable installation by forcing the installed media to the maximum depth tightly in proximity to the cutting operation itself.

FIELD OF THE INVENTION

This invention relates to and is used for installing low voltage circuits (i.e. wire or small cable) or for the installation of fiber optic media in existing residential or light commercial locations. It is an improvement of existing trenchers in that the installer would walk behind, and control similarly to motor powered lawn or garden devices such as tractors, tillers, movers or edgers.

DISCUSSION OF PRIOR ART

Although most prior trenchers and trench digging units—such as U.S. Pat. No. 4,812,078 to Rivard (1989)—are good for installing pipe and digging deep trenches, they can be overkill for wire and cable installations, where a smaller trench is needed. Utility installation contractors have used disc trenchers for years to cut through rock and other debris that other trenchers simply could not penetrate. Utility disc trenchers, however, are useless for shallow wire installations, which include, but are not limited to, underground fences and television cable.

Previous designs for wire and cable trenchers connected the driving mechanism to the trenching mechanism. Thus, the only speed at which the trenching mechanism could operate was the driving mechanism's speed. Such trenchers were unable to cut straight, dependable trenches through underground materials other than soil, such as gravel, hard-packed clay, granite, shale, sandstone, lime stone, concrete, and tree/bush/plant roots. U.S. Pat. No. 5,320,451 to Garvey, et al. (1994), for example, is a tiller attachment for laying cables that connects the “cutting wheel” to the “drive shaft.” So, when the “cutting wheel” encounters an underground material that is harder than the soil, the speed of the driving mechanism and the trenching mechanism stay the same. Hence, the “cutting wheel” would be forced over the harder material rather than through it, and the resulting trench would vary in both depth and direction.

Moreover, other wire and cable trenchers, such as U.S. Pat. No. 5,320,451 to Garvey, et al. (1994), have rigidly mounted trenching blades. Rigidly mounted trenching blades cause the wheels of the trencher to skid sideways when negotiating a turn because the blade is buried in the ground and cannot pivot to facilitate steering of the machine.

Finally, prior wire and cable trenchers, like U.S. Pat. No. 6,189,244 to Johnson (2001), use trenching blades that cut trenches so wide that the path must be backfilled. In other words, the path that the blade cut would need to be refilled over the cable or wire.

BACKGROUND OF THE INVENTION

This mechanized unit or mechanized unit attachment (“unit/attachment”) is designed for installing underground pet fence wiring. Variations on this unit/attachment would allow it to be used for installing other low-voltage outdoor wiring, such as television cable, dog fencing, low voltage landscape lighting, and fiber optic media.

This unit/attachment features a mechanized driving unit and a mechanized trenching unit that operate independently of each other. Hence, the unit/attachment can be driven at a drive speed that is other than the rotation speed of the cutting blade. This allows the unit/attachment to cut easily through hard underground materials such as gravel, hard-packed clay, granite, shale, sandstone, limestone, concrete, and tree/bush/plant roots. By increasing the blade rotation speed and decreasing the drive speed this unit can virtually cut through any obstacle.

The unit/attachment also features a pivoting blade assembly, and pivoting wire shoe, also referred to as a wire feeder, that follows the blade. Thus, the unit/attachment can easily negotiate turns; and, using this trencher, the operator may easily and rapidly trench for miles without having to completely stop or struggle in order to make a turn.

This unit/attachment's traction and stability are superior to that of earlier models. Hence, it is unparalleled for trenching unstable terrain, and can stand up to rugged use while retaining its maneuverability and ease of operation. In fact, this trencher reduces the need for side-to-side movement, allowing for a straighter, more stable trench.

Further, this trencher features either one (1), or two (2) spool-holder(s). Each spool-holder has a capacity of up to 3,000 feet of 18 ga wire, allowing enough wire to cover up to forty (40) acres, which is substantially more than previous trenchers have allowed.

This trencher uses high-speed, motor-driven, uniquely-designed, abrasion-resistant steel blades of varying size, width, and teeth-type (including, but not limited to, carbide and shark teeth). These blades dig up to a maximum depth of 5.5 inches, allow trenching through all soil types, and can cut through various types of solid materials, including, but not limited to, gravel, hard-packed clay, granite, shale, sandstone, lime stone, concrete, and tree/bush/plant roots. These blades create shallow, narrow trenches so small that they eliminate the need for back-filling, and prevent turf disruption, as well as over-excavation. The dependable depth, at which these blades trench combined with the wire fence that insures wire placement to the bottom of that trench, ensures superior circuit performance of animal fences and the like.

The specially designed wire shoe or wire feeder allows for the replacement insertion and removal of wire without cutting or damaging it.

The handlebars and controls pivot to the side, and fold down for ease of storage and transportation. The mechanical connection between the drive mechanism and the trenching attachment is done via side-to-side pivot. This allows the system to tightly maneuver and reduces the turning radius of the overall system.

The driving mechanism has variable speed and is controlled by a hand lever, that does not require gear-shifting of any kind. The handles fold-down to allow the trencher to be easily stored, transported or shipped. It also allows the operator to trench around low-ceiling areas, under tree branches, or next to low walls and fences while the operator maneuvers the trencher from the other side, in the clear.

Further objects and advantages of the invention will become apparent from a consideration of the drawings and ensuing description.

BRIEF SUMMARY OF INVENTION

The subject of this invention are improvements to trenchers that install low voltage wires, cables, and fiber optic media. These improvements have to do with ease of use, quality of the installation, and ultimately the safety of the user. When the drive speed and the cutting speed are independently controlled ability to cut through obstacles increases and with it the depth of cut is more dependable. Combining these features with forcing the wire, cable or media to the cut depth ensures consistent results. The inventor has taken great strides to increase quality of the end product while keeping costs reasonable. This invention is truly the new state of the art in walk behind trenchers.

BRIEF DESCRIPTION OF THE DRAWINGS

The object and improvement of this invention is best understood from the wording of the detailed description when taken in context with the drawings supplied here within. These drawings are detailed to be informative and may not reflect the actual item, scale, or proportions. They are not intended to be the complete representation of the invention, and should not be interpreted in a way that limits the scope of the invention otherwise detailed in other parts of this document.

FIG. 1 drawing of the complete drive and trencher attachment.

FIG. 2 drawing of the pivot connection between the drive and trenching attachment

FIG. 3 drawing of the trenching attachment

FIG. 4 drawing of the blade quick-change mechanism

DRAWINGS—Reference Numerals

-   -   100—drive mechanism     -   101—trenching attachment     -   102—pivot between drive and trenching attachment     -   103—wire spool holder     -   200—hinge assembly     -   201—bushing arm     -   202—hinge pin     -   203—retaining clip     -   300—trenching assembly frame     -   301—hydraulic motor     -   302—wire guides     -   303—wire placement shoe     -   304—wire placement shoe pivot     -   305—height adjustment wheel     -   306—quick connect hydraulic hoses     -   400—quick-change blade assembly     -   401—carbide blade     -   402—quick-change hub     -   403—hub shaft     -   404—removable blade hub     -   405—hardened dowel pin     -   406—retaining ring (o-ring)     -   407—hub hole

DETAILED DESCRIPTION AND PREFERRED EMBODIMENT

FIG. 1 shows a complete trenching system that includes the drive mechanism 100, and the trenching attachment 101. These two portions of the system can be used separately with various other drive devices or attachments as would be appropriate. The two are connected by a pivot 102, which is a key feature of this invention for it allows the unit to tightly turn and to allow the user to maneuver where attachments or blades that are rigidly attached cannot.

FIG. 2 shows how the drive unit 100 and the trenching attachment 101 combine to form the system herein described. This attachment via pivot 102 is important because it suspends the trenching attachment 101 vertically while allowing that trenching attachment 101 to move horizontally. The vertical stability is gained by use of a hinge 200 like mechanism with the attachment held by a bushing 201 and a hinge pin 202 with retainer 203 to prevent the hinge pin from working free. The horizontal motion is free and the blade is allowed to arc to the extent necessary by the maneuver. This substantially improves the turning radius while reducing the stress on the blade itself. Such stress often is shown by chipping and/or loss of the carbide teeth braised to the blade.

FIG. 3 the trenching attachment consists of a frame 300, hydraulic motor 301, a quick-change blade assembly 400, wire guides 302, wire placement shoe 303, wire placement shoe pivot 304, and trench height adjustment wheel 305. This combination allows for variable depth wire or cable installation by having the depth of the trench set by the height-adjusting wheel 305 adjusted to the required depth. It allows for separately adjustable cutting blade speed by means of hydraulic motor 301, which is connected by flexible hydraulic hoses 306 to the drive unit, which incorporates a hydraulic pump attached to the gasoline motor drive. The result is that this hydraulic motor 301 is hydraulically controlled and inasmuch has fully independent speed control from the speed of the drive wheels. Such control allows this system to cut through obstacles where other systems raise up and glaze over these obstacles.

FIG. 4 the quick-change blade assembly 400 has a custom carbide tooth blade 401 of various tooth counts and profiles attached to a quick-change hub 402. This hub is made up of four (4) key components hub shaft 403, removable blade hub 404, hardened dowel pin 405, and retaining ring 406. The combination of these allows the user to quickly remove the blade by moving the retaining clip out and away from the dowel pin 405 that holds the hub shaft 403 and blade hub 404 together. Once the retaining ring 406 is moved the dowel pin 405 is easily removable by hand or with a small rod or screwdriver. The dowel pin's removal allows the user to easily pull the blade hub 404 from the hub shaft 403 even if the blade 401 is trapped in rock or other solid material. Once the blade 401 is freed reattachment to the hub shaft 403 is simple by placing the blade hub 404 on the hub shaft 403, and returning the dowel pin 405 to the hub hole 407 and returning the retaining ring 406 (or in our case the o-ring) to surround the pin 405 itself. 

1. An apparatus for installing small wires and cables underground that comprises: A. handlebars placed in a manner that allows the operator to safely push and guide said apparatus; B. a driving mechanism; C. a hydraulic pump installed so that said driving mechanism's motorization causes the oil of the pump to flow; D. a trenching mechanism; E. a hydraulic motor installed in said trenching mechanism in such a manner that its speed is controlled separately from the speed of said driving mechanism; F. a trenching blade that is made from the abrasion-resistant group of metals or some similar material; that has carbide, or some other type of teeth that are machined, cast, molded, welded or otherwise incorporated into said trenching blade; and that is connected to said trenching mechanism; G a wire feeder that is connected to said trenching mechanism in a manner that allows the wire to be fed into the trench after said trenching blade has cut the trench; H. one or more spool-holders that are connected to said apparatus in a manner that allows the wire, cable, or similar material to flow from its source to said wire feeder and from said wire feeder into the trench; I. a pivoting device that connects said driving mechanism to said trenching mechanism and allows for the oil from the pump in said driving mechanism to flow to the hydraulic motor in said trenching mechanism; J. a gauge wheel connected to said apparatus in such a manner that allows for said gauge wheel to adjust the height of said trenching blade and said wire feeder whereby the wire, cable, or similar material can be placed at the bottom of the trench, and easily inserted and/or removed without cutting or damaging the said wire, cable, or similar material; and whereby said gauge wheel can be dropped into a caster position allowing said trenching blade to be free of the ground while walking to or from the work site; Whereby said apparatus in claim 1 can vary its driving speed and trenching speed independently, vary its trenching depth and width, and easily negotiate turns.
 2. Said trenching blade in claim 1 that cuts a trench from 5/16″ to ⅜″ wide.
 3. Said trenching blade in claim 1 that cuts a trench from 9/16″ to ⅝″ wide.
 4. Said trenching blade in claim 1 that cuts a trench from 1″ to 1¼″ wide.
 5. Said trenching blade in claim 1 controlled by a lever that allows the blade to rotate either forward (in the same direction as the wheels) or backward (in the opposite direction of the wheels); whereby said trenching blade can easily cut under normal trenching conditions such as lawn, gravel driveways, hard packed clay, etc. when said trenching blade is required to turn backward; and whereby, under other trenching conditions, such as swampy lake shore areas or soggy fresh fill, said trenching blade may be required to turn forward.
 6. Said handlebars in claim 1 designed to be folded down; whereby said apparatus in claim 1 can be stored and shipped with ease.
 7. Said handlebars in claim 1 designed to pivot; whereby the operator may trench under low hanging branches or along wire or wooden fences while the operators is in the clear.
 8. Said driving mechanism in claim 1 controlled by a lever that allows said driving mechanism to operate at a variable speed; whereby the operator may select a speed from 0 to a comfortable walking speed without gear shifting.
 9. A unit for installing small wires and cables underground that attaches to an apparatus comprising of: A. a trenching mechanism; B. a hydraulic motor installed in said trenching mechanism in such a manner that its speed is controlled separately from the speed of the driving mechanism; C. a trenching blade that is made from the abrasion-resistant group of metals or some similar material; that has carbide, or some other type of teeth that are machined, cast, molded, welded or otherwise incorporated into said trenching blade; and that is connected to said trenching mechanism; D a wire feeder that is connected to said trenching mechanism in a manner that allows the wire to be fed into the trench after said trenching blade has cut the trench; E. one or more spool-holders that are connected to said unit in a manner that allows the wire, cable, or similar material to flow from its source to said wire feeder and from said wire feeder into the trench; F. a pivoting device that connects said unit to said trenching apparatus; G. a gauge wheel connected to said unit in such a manner that allows for said gauge wheel to adjust the height of said trenching blade and said wire feeder whereby the wire, cable, or similar material can be placed at the bottom of the trench, and easily inserted and/or removed without cutting or damaging the said wire, cable, or similar material; and whereby said gauge wheel can be dropped into a caster position allowing said trenching blade to be free of the ground while walking to or from the work site; Whereby said unit in claim 9 can vary its driving speed and independently from the trenching apparatus's speed, vary its trenching depth and width, and easily negotiate turns.
 10. Said trenching blade in claim 9 that cuts a trench from 5/16″ to ⅜″ wide.
 11. Said trenching blade in claim 9 that cuts a trench from 9/16″ to ⅝″ wide.
 12. Said trenching blade in claim 9 that cuts a trench from 1″ to 1¼″ wide.
 13. Said trenching blade in claim 9 controlled by a lever that allows the blade to rotate either forward (in the same direction as the wheels) or backward (in the opposite direction of the wheels); whereby said trenching blade can easily cut under normal trenching conditions such as lawn, gravel driveways, hard packed clay, etc. when said trenching blade is required to turn backward; and whereby, under other trenching conditions, such as swampy lake shore areas or soggy fresh fill, said trenching blade may be required to turn forward. 